This invention relates to a coupling device for an appliance for domestic use.
Coupling devices of this type for kitchen machines are known from the art. For example, FR 1467108 describes a device in which a socket arranged on a tool shank hooks elastically into the lower region of the drive part. For this to happen the drive part has at its lower end a latch which, under the action of a helical spring, engages radially in a groove provided on the outer circumference of the socket. In this arrangement the latch can be released by an actuating button which in the latched position projects sideways out of the drive part.
From FR 1467108 there is also known an ejecting device which is integrated in the drive part. According to this prior art, a helical spring is biased when the tool shank is pushed in and used as an ejector when released.
Furthermore, from EP 0692215 A1 there is known a handheld blender with a drive part and an interchangeable tool shank in which a tool shaft is rotatably mounted. To fasten the tool shank to the drive part an expansion clamp of the drive part engages in a mounting groove of the tool shank. To release the tool shank the expansion clamp, which is constructed as a metal spring, is pushed by means of a pushbutton, which is constructed as a separate component, in the direction of an opposite lying pushbutton.
It is an object of the present invention to provide a simple and low-cost solution for connecting a tool shank to the drive part of an appliance for domestic use, particularly a handheld blender or immersion blender.
In general, in one aspect there is a coupling device with a locking device having at least one locking element being arranged on a coupling section of a drive part. In a locked state, the locking element engages with a detent element of a tool shank. The locking device is constructed as an annular spring element and in the area of each locking element provision is made for an actuating device. When actuated, the actuating device causes the spring element to be deformed elastically such that the locking element becomes disengaged from the detent element. A particularly simple coupling device affording low-cost manufacture is provided by the construction of the invention. The device of the present invention may find application not only on handheld blenders such as immersion blenders but also on stand-alone kitchen machines or other electrical appliances for domestic use. The coupling section of the drive part may be constructed, for example, essentially as a cylindrical end portion having arranged in its interior the locking device. The upper part of the tool shank is likewise of an essentially cylindrical configuration at its inner circumference enabling it to slide over the coupling section of the drive part quasi like a sleeve to be centered and axially fixed in place on the cylindrical end portion. Furthermore, rotatably mounted in the tool shank is a tool shaft whose one end is adapted to be coupled with the drive shaft of the drive part and whose other end projects into the blending space of a bell-shaped shield and is securely connected to a processing blade, such as was initially referred to in the prior art.
It will be understood, of course, that other annular configurations of the spring element, e.g., circular, prismatic, elliptical or other forms of ring, are also possible. With these configurations the upper part of the tool shank, which is constructed essentially as a sleeve, is shaped to conform to the shape of the coupling section of the drive part in order to be able to plug these parts together. The detent element, which here is constructed preferably as a depression provided on the inner circumference of the tool shank, may be constructed as a circumferential groove, for example, or as a single elongated slot. In the event of the locking device being constructed as an ellipse, the points furthest apart from each other lie on the long diameter of the ellipse. If the spring element is shaped as a rhombus, the points furthest apart from each other lie on the long diagonal.
The locking element may be formed by a projecting lug or a bead or a depression, for example, which is integrally connected as a one-piece construction with the spring element and then engages in a corresponding depression or lug or other projection on the tool shank. The actuating device involved may be a bead which is formed on the spring element and has the function of a pushbutton. A multiple function results from the fact that both the actuating device and the locking element are integrally connected as one piece with the spring element, thereby reducing the number of additional components and having the actuating and locking function performed by a single component.
Through the superimposed arrangement of the actuating device and the locking element the locking element is displaced radially inwardly when the spring element on the actuating device is pressed, as the result of which it slides out of the detent element, thus releasing the tool shank for removal. According to the invention the actuating element may simultaneously form the locking element as well. According to the invention the spring element is deformed by the actuating element being pressed on the one side while the spring element takes support upon the housing of the drive part on the other side.
By virtue of the diametric arrangement of the locking and actuating elements of some embodiments, it is possible to press together the spring element in simple manner and with little force using the thumb and index finger of one hand, as the result of which the locking elements move likewise in inward direction. When released, the spring element and the locking elements return to their initial position.
In some embodiments, provision is made for at least one opening on the outer wall of the coupling section of the drive part. The openings for the actuating elements may be elongated or oval slots or, alternatively, openings shaped in a rectangular, circular or some other configuration. In the locked state the actuating elements project out through these openings and are therefore freely accessible from the outside for actuation. When actuated by hand the actuating elements partly disappear in the openings of the outer wall of the coupling section of the outer part, as the result of which the locking elements also move inwardly and slide out of their detent elements, as the result of which the tool shank is in turn released and allowed to slide downward from the coupling section and drive part.
In some cases, actuating devices are diametrically opposed on the spring element projecting outwardly through the openings provided on the drive part, making it possible for the spring element to be actuated particularly effectively and easily from the outside, because the spring element is essentially symmetric in construction and pressed together uniformly from both sides when force is applied.
In some embodiments, the superimposed arrangement of the locking element and the actuating device results in the path traveled on the actuating device being equal to the path traveled on the locking element, i.e., a direct transmission of travel results with minimum actuating forces and displacement travels, leading ultimately to a simple and direct unlocking operation of the coupling device.
In another aspect, the locking device can be fabricated from a suitable thermoplastic material. Suitable materials to be considered include, for example, elastic polypropylene, polyethylene or polyamide. These materials can be used for injection-molded parts in a simple and low-cost manner. The inherent elasticity of these plastics guarantees that the spring element recovers its original form after being accordingly deformed as required. Furthermore, a multiplicity of functions can be performed by a single component through its construction as a one-piece plastic part.
In yet another aspect, the locking device can include at least one ejector disposed in a 90-degree offset relation to the locking element. Furthermore, the functions of the ejector and the locking elements are skillfully interconnected because the ejector is arranged at an angle of 90 degrees to the locking elements in the case of a spring element of cylindrical configuration, on the short diameter in the case of a spring element of elliptical configuration, and on the short diagonal in the case of a spring element of rhombic configuration. When the locking device is accordingly actuated by means of the actuating elements the spring element is deformed for the releasing operation, thus enlarging the regions of the spring ring around the ejectors or the lengths of the short diagonals or short diameters whilst compressing the actuating region of the spring element. The ejectors are thereby pressed against the obliquely extending inner circumference of the tool shank, as the result of which the locking elements are unlocked and the tool shank simultaneously decoupled from the drive part, pushed away and thereby ejected axially in the longitudinal direction of the drive part.
Some embodiments include ejectors diametrically opposed on the spring element. The ejectors can have ramp surfaces which, when actuated radially, effect an axial ejecting movement in the longitudinal direction of the drive part. A flat ramp pitch is selected so that the actuating forces are not too high for the operator but the travel is still sufficient for the tool shank to be visibly disengaged from the drive part.
In yet another embodiment, provision is made on the locking device and in the coupling section of the drive part for corresponding guide devices that guide the spring element radially towards the drive part. Suitable guide devices, which may be formed, for example, by grooves provided on the spring element and guide ribs on the drive part, are used to prevent the spring element from skewing, for example, thus ensuring a reliable function.
In another aspect, the locking device includes a captivating device comprised of the ejector formed on the spring element, wherein the ejector engages within a passage formed on the drive part. A captivating device of this type may be provided, for example, by having either the ejectors or the locking elementsxe2x80x94preferably the ejectors in the embodimentxe2x80x94always engaged with the passages formed on the drive part. Fixing the spring element in the drive part in this manner facilitates the assembly operation significantly because, once installed, the spring element is fixed in its position. Slipping out of the predefined position and jamming with other components is thereby prevented. The ejectors penetrate the drive part and project out of it far enough in radial direction as to latchingly engage in depressions formed on the tool shank in order to act as detent elements when the tool shank is inserted.
In some embodiments, the locking elements are arranged on first connecting bars integrally connected with the spring element. It is thereby possible for the locking elements to snap in place during the coupling operation, without the actuating devices being in the way. This is achieved by spatial separation of the locking elements relative to the actuating devices. When mounting the tool shank it is thus possible for the locking elements to be pressed, without actuating the actuating device, back into the corresponding opening in the outer wall of the coupling section until they are aligned with the depressions on the inner circumference of the tool shank. At this moment the locking elements snap back on account of the spring action of the vertical connecting bar. The coupling connection is now engaged and locked. Unlocking is now only possible by actuating the actuating devices.
To improve the snap-action effect of the locking elements, the locking elements can be constructed in a wedge-shaped configuration, with the detent elements in the form of depressions whose horizontally extending walls abut against abutment surfaces on the locking elements and whose obliquely outwardly extending centering surfaces abut against sliding surfaces on the locking elements shaped to conform to the shape of the centering surfaces of the detent elements. On the one hand the locking elements thus act as a barb, on the other hand the centering surfaces on the tool shank cooperate with the sliding surfaces on the spring element, resulting in the spring element invariably urging the tool shank into the drive part without play, as the result of which the walls are biased against the abutment surfaces because the spring element in the drive part always maintains a small bias.
In some cases, the ejectors are arranged on second connecting bars which are integrally formed with the spring element. In the cases, the tool shank can slide on the wedge-shaped ejector as on a ramp during the decoupling operation. The additional spring action through the second connecting bars helps to control the ejection pressure. It also prevents skewing.